Retractable cord reels have been used in various applications to retractably store various types of cables. Typically, a reel might have a stationary end and a retractable end, the retractable end capable of extension from and retraction back into the reel, and a stationary end that does not move during extension or retraction. Such a configuration reduces the mess typically associated with loose wires, as well as dangers related to loose cords, hazardous operating environments and the like.
The use of fiber optic cable and associated components to communicate information has increased dramatically, due in part to the increased need to transmit larger amounts of information more rapidly (e.g., real-time video). These higher data speeds can be met using an optical fiber medium. Essentially, transmission of information using fiber optics is achieved using light pulses that traverse along a glass or plastic optical wire or optical fiber. Thus, as the need for faster communication has grown, optical fiber, because of its ability to transmit more information at higher speeds, is an improvement over conventional copper wire for providing various communication links. Further, not only is more data transmitted at higher speeds, but optical fiber is less subject to interference (e.g., electromagnetic interference), thereby reducing the need to shield, retransmit or amplify signals. However, existing available structures are unsuitable for addressing the challenges posed by optical fiber.
In one prior art retractable reel, the extendable and stationary portions of a cord may be separate, but may be connected for example by brush-like contacts. The brush-like contacts slide along the inside or outside of the rotating spool, effectively maintaining a continuous contact between the moving parts. However, such arrangements would require lightpipes or similar structures which enable the communication of data between the cables and thus create undue expense and complexity. Furthermore, while high data transfer may be enabled over fiber optic cable, the typical profile of such case is flat, and is thus less tolerant to twisting in a cord reel in a retractable application, especially over repeated use.
A second type of retractable cord reel has been developed that maintains a constant connection between the retractable and stationary ends of the cord through the use of a spool divided into two chambers: one for holding a round retractable cord, and a second, expansion chamber holding a coil of flat cord that can be expanded within the reel housing. Attempts have been made to use a round cord as the stationary expanding cord, but it is inefficient and prone to jamming. Thus, the flat/round combination is preferred. The retractable cord is connected to the stationary end through an internal coil, which may expand through its chamber during rotation of the spool. An example of this type of reel is disclosed in U.S. Pat. No. 5,094,396 to Burke, the disclosure of which is hereby incorporated by reference.
The expansion cord length may be minimized by permitting expansion of the cord followed by a reverse-direction contraction of the cord. This process is illustrated in U.S. Pat. No. 6,372,988 to Burke, the disclosure of which is hereby incorporated by reference. An additional approach is shown in U.S. Pat. No 8,387,763 (the disclosure of which is also incorporated herein by reference) for reducing mechanical strain from the repeated back and forth bending of the retractable segment of the cord, e.g., though the use of a ferrule.
While these earlier approaches improved upon the prior art, such designs still limitations in the applicability to a single, continuous cord segment. For instance, the use of a single round cord as the stationary expanding cord is prone to jamming, while use of a single flat cord is prone to twisting and excessive wear. Also, fiber optic cables are prone to developing stresses within the fibers, so there is a problem with providing a cord or cable design that provides sufficient strength for repetitive winding and unwinding while sufficient give within the cord to avoid undue stresses being applied to the fibers themselves. Moreover, such existing approaches do not address the complexity and risk for entanglement and failure when the application requires running multiple cords (e.g., data and power) off of the same reel. Thus, there is need for an improved configuration and design which enables cost efficient improved durability for a fiber optic cord reel assembly including portions including a retractable round cord and a stationary, expanding flat cord in a multi-chamber cord reel assembly.